A study of antimicrobial activities of local anesthetics, and conbined effects of anesthetics/antibiotics on clinical isolates from oral and maxillofacial infections

Abstract

局麻薬の臨床分離株に対する抗菌力, ヒト抜歯創における局麻薬停滞性および抗菌薬との併用効果について検討し, 以下の結果を得た。1) Streptococcus sp., S. aureus およびP. aeruginosa に対する lidocaine と prilocaine のMICを測定したところ, それぞれ2500～7500μg/ml以上で抗菌力が確認された。2) 抜歯創における lidocaine 濃度は, 注射後1～45分で8.4～2590μg/mlに分布し, 全症例 (182例) の平均値は426.3μg/mlであった。3) 下顎第三大臼歯の135例では, 80%が10～15分で抜歯されており, 平均188.9～283.2μg/mlの lidocaine 濃度が認められたが, MICから判断すると lidocaine 単独での抗菌力は臨床的に期待できない結果であった。4) CCL, ABPCおよびOFLXの抗菌力について, 250μg/mlの lidocaine を添加してMICを測定した結果, 一部の菌株では1～2管程度のMICの低下がみられたが, なかでも Streptococcus sp. に感受性の改善した菌株が多かった。5) Streptococcus sp. に対するCCL, ABPCおよびOFLXの抗菌力について, lidocaine を25, 250, 500μg/mlに調整して添加したが, 感受性の変化はlidocaine 濃度に関係なくみられた。以上, 一部の菌株では低濃度の局麻薬存在下に抗菌薬の感受性が増強され, 術前から抗菌薬を投与した場合にはさらに感染予防効果が高くなる可能性が示唆された。 / Antimicrobial activities of the local anesthetics against clinical isolates from oral and maxillofacial infections, ledocaine levels of tooth extraction wounds in human, and the combined antimicrobial effects of lidocaine with antibiotisc were determined. The folloewing results were obtained. 1) The MICs of lidocaine and prilocaine against Streptococcus sp., S. aureus and P. aeruginosa were 2500 to 7500μg /ml. 2) Lidocaine levels of tooth extraction wounds ranged from 8.4 to 2590μg /ml in 1 to 45 minutes after injection, and the mean lidocaine level was 426.3μg /ml. 3) Lidocaine levels of the third molars in 135 cases showed 188.9 to 283.2μg /ml in 10 to 15 minutes after injection, however, it was thought that these lidocaine concentrations would not be able to act as antimicrobial agency according to the MICs of lidocaine. 4 ) When the MICs of CCL, ABPC and OFLX in combination with lidocaine of 250μg /ml were determined, some strains especially in Streptococcus sp. showed 2 to 4 fold greater antimicrobial activities than those of antibiotics alone. 5) The MICs of CCL, ABPC and OFLX against Streptococcus sp. in combination with different lidocaine levels (25, 250, 500μg /ml) , were not changed in sensitive strains with no relation to the concentration of lidocaine in this study. From the above results, antimicrobial activities of antibiotics against some strains may be improved with low dose local anesthetics, so it was suggested that preoperative administration of antbiotics would be helpfull to get greater antimicrobial actimicrobial activities and prophylactic effects with local anesthetics